• Journal of the Korea Organic Resources Recycling Association
• /
• v.30 no.1
• /
• pp.33-39
• /
• 2022

Batch experiments were conducted to find out the effects of various types of magnesium compounds on phosphorus recovery by magnesium ammonium phosphate (MAP) crystallization. The phosphorus recovery from the centrate of anaerobic digested sludge was performed using magnesium chloride, magnesium hydroxide and magnesium oxide under different pH (7.5, 8.0 and 8.5) and Mg/P molar ratio (1.0, 1.5, 2.0, 2.5) conditions. The phosphorus recovery rate increased with increasing pH and Mg/P molar ratio in all magnesium compounds. At pH 7.5, magnesium oxide showed the highest phosphorus recovery rate, followed by magnesium hydroxide and magnesium chloride. However, at pH 8.5, more than 90% of phosphorus recovery rate was obtained in all Mg/p molar ratios. Thus, it is expected that magnesium hydroxide and magnesium oxide are able to replace magnesium chloride as a magnesium source in terms of phosphorus recovery efficiency and cost.

• Journal of Korean Society on Water Environment
• /
• v.31 no.4
• /
• pp.387-391
• /
• 2015

This study was performed to evaluate the effect of pH (8-12) and molar ratio of magnesium and phosphate ($[Mg^{2+}]/[PO_4{^{3-}}]$) (0.6-1.4) on struvite crystallization of anaerobic digester supernatant using seawater as magnesium source. pH range of 9-10 is favorable for ammonium and phosphate recoveries. The recovery efficiency of ammonium was highest at $[Mg^{2+}]/[PO_4{^{3-}}]$ of 1.0 and pH 10. On the other hand, high phosphate recovery efficiency (> 99%) was achieved at ($[Mg^{2+}]/[PO_4{^{3-}}]$) of 1.4 and pH 10. The results demonstrated that seawater can be considered as low-cost magnesium source to recover phosphorus from anaerobic digester supernatant.

• Microbiology and Biotechnology Letters
• /
• v.7 no.3
• /
• pp.165-173
• /
• 1979

Recovery component for cell division in UV-irradiated E. coli B was detected with use of the cell extract of E. coli B/r which is a resistant mutant of E. coli B against UV-irradiation. The active substance was non-dialyzable and increased the activity by adding B-NAD remarkably. One more factor for increasing or promoting the restoration recognized was magnesium. Magnesium was effective to stabilze the substance in procedure of isolation. Two active substances were obtained from sucrose gradient centrifugation. One of them was recovred from the botton area and the other from top area just below below surface. the former was not stabilized by magnesium, while the latter stabilized the activity by it remarkably. The former which did not require magnesium was insensitive to protease and the latter which required magnesium was sensitive to it. Both were insensitive to RNase and DNase. Recovery ratio was doubled by using nitrogen gas than aeration in purification process. DNA-ligase less mutant was revealed same activity on it's recovery ratio with the parent strain of E. coli K-12. The active substance stimulating the filament cell may exist as a complex which is inactivated easily in the dissociated state ana requrie B-NAD or magnesium.

• Journal of Environmental Science International
• /
• v.10 no.5
• /
• pp.381-386
• /
• 2001

The characteristics of precipitation separation and solvent extraction separation of magnesium from the waste bittern were studied experimentally In the result of precipitation separation, the size of magnesium hydroxide precipitated was not affected on pH, but decreased with increasing the precipitation temperature. The purity of magnesium oxide precipitated was increased with pH beyond pH 11. From the solvent extraction separation, the equilibrium extraction ratio of magnesium was increased with pH and temperature of extraction phase, the concentration of stripping phase, and with decreasing pH of stripping phase. The extractant of Aliquat 336 and Acid 810 mixture was more effective than that of DCH18C6 and $D_2EHPA$ mixture in the extraction separation of magnesium.

• The Korean Journal of Pain
• /
• v.13 no.1
• /
• pp.31-37
• /
• 2000

Background: Recent studies suggested that a preoperative block of N-methyl-D-aspartate (NMDA) receptors with NMDA antagonists may reduce postoperative pain. In this double-blind study, magnesium sulfate, a natural NMDA receptor antagonist, was administered preoperatively to investigate the effects of magnesium sulfate on postoperative pain and pulmonary function. Methods: Seventy patients who were to undergo gastrectomy under general anesthesia were randomly assigned to one of three groups. Groups 2 and 3 received intravenous magnesium, preoperatively (Group 2: 50 mg/kg bolus, 7.5 mg/kg/hr for 20 hr, Group 3: 50 mg/kg bolus, 15 mg/kg/hr for 20 hr). Group 1 received normal saline as the control group. Visual analog scale (VAS) for postoperative pain and mood, cumulative analgesic consumption, recovery of pulmonary function and side effects were evaluated at 6, 24, 48 and 72 hours after the operation. Results: In Groups 2 and 3, plasma concentration of magnesium were significantly higher than in Group 1 at 6 and 20 hours after infusion (P<0.05). There were no significant differences in the analgesic consumption, and recovery of pulmonary function and the incidence of side effects at 6, 24, 48 and 72 hours after the operation among the three groups. In Group 3, pain scores at rest measured 24 and 48 hours after operation were lower than the control group, and pain scores when deep breathing were significantly lower than the control group at postoperative 6, 24, 48, and 72 hours. Conclusions: We conclude that intravenous infusion of greater amount of magnesium has little effectiveness in reducing postoperative pain. However, further studies are needed to characterize the clinical significance of these effects on postoperative pain.

• Resources Recycling
• /
• v.25 no.4
• /
• pp.32-41
• /
• 2016

The precipitation test, which is the last step of magnesium recovery process consisting of three processes (pre-precipitation, selective dissolution of magnesium, precipitation) is performed to obtain magnesium sulfate powder from seawater. In the study, we succeed in precipitating the magnesium sulfate by adding acetone into the solution of magnesium over 4 times concentrated from seawater. The yield efficiency of magnesium sulfate increases with increasing pH and the ratio of added acetone. More than 99% of magnesium is obtained as magnesium sulfate hydrate ($MgSO_4{\cdot}6H_2O$) under the following conditions; pH 1.0 ~ 1.5, and the ratio of solution and acetone 1 : 1.5 (v:v). The acetone used in the precipitation process is recovered by the fractional distillation.

• The Journal of Korean Academy of Prosthodontics
• /
• v.41 no.5
• /
• pp.551-564
• /
• 2003

Statement of problem : Magnesium oxide may increase pH of alginate, and supply magnesium ions to the polymerization reaction of alginate. Purpose : This study was designed to evaluate the influence of incorporation of magnesium oxide to alginate composition. Material and Method : Seven kinds of experimental alginates were prepared and used for the experiments. Components with unchanging concentrations were sodium alginate 15%, calcium sulfate 14%, sodium phosphate 2%, and zinc fluoride 3%. Contents of magnesium oxide were varied as 0%, 1%, 2%, 3%, 4%, 5%, 6%. Diatomaceous earth were added to each experimental groups as balance to be 100%. Control group was a MgO 0% group. Working time, setting time, elastic recovery strain in compression, compressive strength and tear resistance were measured were measured. Sample size for each groups were 10. Arithmetic means were used as each groups representative values. Regression test between MgO contents and results, Duncan's multiple range test, and One-way ANOVA test were done between groups at level of 0.05. Results : 1 Magnesium oxide made the working time and setting time as longer(p<0.0001). 2 Magnesium oxide did not alter the elastic recovery(p>0.05). 3. Magnesium oxide contents between 2% and 4% exhibited the lowest strain in compression on alginates(p<0.0001). 4. Magnesium oxide made the compressive strength and the tear resistance stronger(p<0.0001). Conclusion : These results mean that setting time of alginate maybe controlled and that mechanical properties maybe improved by the incorporation of magnesium oxide into alginate, without any reduction of elasticity.

• Journal of Korean Society on Water Environment
• /
• v.32 no.4
• /
• pp.343-348
• /
• 2016

A chemical sequencing batch reactor was operated to test the feasibility of nutrient recovery from a biological livestock wastewater treatment plant. Both phosphate and ammonia could be successfully recovered as magnesium ammonium phosphate (MAP) crystals. The contents of TP and TN in the recovered MAP crystals were 26.2% and 4.0%, respectively. Zn, Cr and Ti were identified in the crystals, but the contents remained below the Korean standard for an organic fertilizer. Chemical analyses confirmed that the MAP crystals could be useful phosphate fertilizers. On the other hand, the results of physical analyses using an X-ray diffractometer and an energy dispersive X-ray spectrometer strongly suggested that crystalline materials like magnesium potassium phosphate (KMP) and hydroxyapatite (HAP) were also formed during the MAP crystallization, depending on the availability of K⁺ and Ca²⁺.

• Animal cells and systems
• /
• v.7 no.2
• /
• pp.169-171
• /
• 2003

Sodium, potassium, calcium, zinc and magnesium levels in the serum of 31 patients diagnosed as acute myocardial infarction were analyzed on admission (within 24 Hours) and after 48 hours. The results were compared with those of 26 age matched controls. No significant difference was observed in the mean sodium, potassium, calcium and zinc levels between the cases and controls. Compared to the controls, however, the variation in the level of magnesium is highly significant at the time of admission as well as after 48 hours. When the risk factors like diabetes mellitus, hypertension, smoking and alcohol were considered, it is found that there is no significant difference between the risk groups as well as between the patients. The alteration in magnesium level in acute myocardial infarction is independent of these risk factors. Within the first 24 hours, the significant decrease in serum magnesium (35-51％ fall when compared with the control group), correlates with its entry into the cell following ischemia. From this hypomagnesemic state, it rises to 9-22 times after 48 hours. This hyper-magnesemia after 45 hours is probably due to the shift of magnesuim from the intracellular fluid compartment to the extracellular fluid compartment that follows cellular recovery. Therefore, including magnesium in the immediate management of acute myocardial infarction will be beneficial in the early recovery.

• Journal of Biosystems Engineering
• /
• v.31 no.1 s.114
• /
• pp.46-51
• /
• 2006

This study was carried out to recover phosphorus in animal wastewater using a magnesium source. $MgCl_2$, as a magnesium source, was shown a SP (soluble phosphorus) recovery rate of 98% in both the aeration and the NaOH tests to adjust pH around 8.5. In case of MgO, the recovery rate of SP were 88% with the aeration and 58% with the NaOH. In case of ammonia nitrogen recovery, $MgCl_2$ was shown the recovery rate of 17% with aeration and 18% with NaOH. MgO was shown the ammonia recovery rate of 18% with aeration and 11% with NaOH. At low temperature of $6-8^{\circ}C$ with the animal wastewater from piglet stall, the recovery rate of SP was shown 95% with NaOH and 92% with aeration using $MgCl_2$. The recovery rate of ammonia nitrogen was shown 9% with NaOH and 12% with aeration, respectively. It was observed that the pH can be raised by aeration. The reaction was completed within 5 minutes and the struvite cristal structure was formed and could be observed with an electronic microscope.